PROJECT SUMMARY Overall Component COVID19 is a severe ongoing pandemic. Our understanding of the immune response to this disease is lacking, which impairs both the development of proper therapeutics and a vaccine. Vaccines are one of the most cost effective and extraordinarily successful medical interventions. Most of those vaccines depend on CD4 T+ cells and their help to B cells. We have developed multiple new techniques to study human CD4+ T cells over the past several years, which have have been implementing in our LJI CCHI. The supplement proposed here will facilitate rapid and vigorous pursuit of an understanding of the T cell responses to SARS-CoV2 in humans, which may help in the development of treatments and vaccines for COVID19.